A new study suggested that public adherence to mask-wearing could lead to more infection if the caveats are not strictly followed.

The study, published in the journal JMIR Public Health and Surveillance, was conducted by a team of health economists and public health faculty at the University of Vermont’s Larner College of Medicine in partnership with public health officials for the state of Vermont.

The study combines survey data gathered from adults living in north-western Vermont with test results that showed whether a subset of them had contracted Covid-19, a dual research approach that few Covid studies have employed.

By correlating the two data sets, researchers were able to determine what behaviours and circumstances increased respondents' risk of becoming sick.

The study found that the key risk factor driving transmission of the disease was the number of daily contacts participants had with other adults and seniors.

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Their findings revealed that those who wore masks had more of these daily contacts compared with those who didn’t, and a higher proportion contracted the virus as a result.

Basic human psychology could be at work, said lead author Eline van den Broek-Altenburg, an assistant professor and vice-chair for Population Health Science in the Department of Radiology at the Larner College of Medicine.

“When you wear a mask, you may have a deceptive sense of being protected and have more interactions with other people,” she said.

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“Messaging that people need to wear a mask is essential but insufficient. It should go hand-in-hand with the education that masks don’t give you a free pass to see as many people as you want. You still need to strictly limit your contacts,” she added.

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The study also found that participants’ living environment determined how many contacts they had and affected their probability of becoming infected. A higher proportion of those living in apartments was infected with the virus compared with those who lived in a single-family home.

For the study, the researchers surveyed 12,000 randomly selected people between the ages of 18 and 70 who had at least one primary care visit at the University of Vermont Medical Center.